AQA A Level Chemistry

Revision Notes

7.6.2 Biodegradability & Disposal of Polymers

Biodegradability

Biodegradable polymers

  • Both polyesters and polyamides can be broken down using hydrolysis reactions
  • This is a major advantage over the polymers produced using alkene monomers (polyalkenes)
  • When polyesters and polyamides are taken to landfill sites, they can be broken down easily and their products used for other applications

Hydrolysis of polyamides

  • Hydrolysis is a breaking up of a molecules using water
  • In acidic hydrolysis, acid (such as hydrochloric acid) acts as the catalyst
    • Polyamides are heated with dilute acid
    • This reaction breaks the polyamide into carboxylic acid molecules and ammonium chloride ions
  • Alkaline hydrolysis
    • The polyamide is heated with a species containing hydroxide ions (eg. sodium hydroxide)
    • This breaks the polymer into the sodium salts of its monomers (dicarboxylic acids and diamines)
    • If the poly amide link used an aminocarboxylic acid as the monomer, then a sodium salt of the original amino acid is reformed

Polymerisation - Amide Hydrolysis, downloadable AS & A Level Chemistry revision notes

When polyamides are degraded by hydrolysis, carboxylic acids and amines are formed

Hydrolysis of polyesters

  • Ester linkages can also be degraded through hydrolysis reactions
  • Acid hydrolysis forms the alcohols and carboxylic acids that were used to form the polyesters

 

Polymerisation - Ester Hydrolysis, downloadable AS & A Level Chemistry revision notes

When polyesters are degraded by hydrolysis, carboxylic acids and alcohols are formed

Disposal of Polymers

Disposal of Polymers
Close

Join Save My Exams

Download all our Revision Notes as PDFs

Try a Free Sample of our revision notes as a printable PDF.

Join Now
Already a member?
Go to Top